280 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



p. 651, with graduated scales for tlie rectangular movements and 



graduated circlo and index. 



The nose-piece is provided with a special adapter to which the 



ohjective may be screwed, aud into which slide the four following 



accessories, each mounted in a separate brass frame : (a) Bertram! lens ; 



(b) quarter undulation plate ; (c) quartz wedge ; (d) Klein's quartz plate. 



The nose-piece has also centering screws. The analyser is inclosed in 



one side of a double-chambered 

 Fig. 41. box, the other side being left 



vacant, so that it may be slid 

 in or out of the tube at will 

 without at any time leaving 

 an opening through which 

 dust may enter. 



Bamberg's Spherometer 

 Microscope.* — Dr. S. Czapski 

 describes this intrument (fig. 

 41) as follows : — B B is a 

 strong brass frame fixed in a 

 circular disc A, to which 

 spherometer rings of different 

 diameters can be fastened by 

 the screws s s. Complete 

 centering of the rings is se- 

 cured by circular projections 

 of rectangular section turned 

 upon the under surface of A. 

 The spherometer ring is either 

 entire or consists (as in the 

 figure) of four hard steel seg- 

 ments S S, which form parts 

 of a complete circle turned 

 upon the lathe. J and L are 

 steel guides for the strictly 

 cylindrical steel tube U, which 

 contains the micrometer Micro- 

 scope M. U terminates below 

 in a steel cylinder D, at the 

 end of which is a small sphere. 

 P is the reflection prism placed 

 under the objective, and in 

 front of it is an aperture 

 in U through which a scale 

 Q, divided to 0*2 mm., and 

 illuminated by the mirror C, 

 is viewed in the Microscope. The scale Q is attached to the frame 

 B by four screws, and adjusted by the nuts 1 1 to the focus of the 

 Microscope. Any vertical movement of the Microscope in its bearings 

 can be measured by the divisions of the scale, which are then seen to 

 travel across its field. The drum gives thousandths of a millimetre 

 direct, and tenths of these can be estimated with safety. Behind U 



Zeitschr. f. Instrumentenk,, vii. (1887) pp. 297-301 (3 figs.)- 



